Constant force peelable seal for container

ABSTRACT

A peelable lid conforms to a container having pointed edges at opposing ends forming an eye or boat configuration. The pointed edges provide starting and stopping points for removal of the lid from the container. The pointed edges minimize the peel front at the start of the removal of the lid and at the end of the container when dislodging the lid completely from the container. The peel front is proportional to the peel force at any given location on the lid, so that the minimized peel front provides a constant peel force during the removal of the lid. The peelable seal may also be formed, by a perforated, scored or otherwise tearable area around the periphery of the lid allowing the peel front to progressively proceed along the periphery of a sealing flange.

This application claims priority of U.S. Provisional Patent Application Ser. No. 60/711,871 filed on Aug. 26, 2005 incorporated herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to peelable sealed packaging, and more particularly to peelable seals requiring a constant force application for removal of the seal covering a container.

BACKGROUND

It is generally known that consumers desire convenience and satisfaction from packaging containers, particularly from containers currently used for packaging food products. Many of today's food product packaging containers include peelable seals or covers having an adhesive along an inside peripheral edge of a lid for adhering to the upper peripheral edge or flange of the container. However, in everyday use it is a common occurrence for the food product to be spilled when a consumer tries to open a peelable sealed package. By way of example and not limitation, many mothers find it necessary to open and repackage peelable sealed fruit cup or yogurt packages for young children to take to school. It has been found that a problem associated with current peelable sealed packaging is the varying amount of force required to remove the peelable seal or lid from the associated sealing surface of the container. The underlying cause of this varying force requirement can readily be seen when calculating the peel front of a peelable seal or lid covering for a circular topped container having an outer flange dimension D and an inner flange dimension d wherein the adhesive covers the circumferential area between the inner and outer flange dimensions. The peel front is initially high and drops to a lowest value adjacent the center of the circular container peripheral flange. The peel front value then steadily increases toward the end of the peel direction A₁. The peel front is proportional to the peel force. Therefore, a variable peel front will result in a variable peel force, and can cause spilling of container contents. Increased spillage of container contents increases customer dissatisfaction with the product.

SUMMARY

It is desirable in the present invention to provide a constant peel front and thereby present the consumer with a constant peel force to remove the peelable seal or lid from the container. A constant peel force will permit the consumer to open a container in a controllable manner resulting in lower spillage rates for the contents of the container. Lower spillage rates can result in greater customer satisfaction with the product. Improved ergonomics enables use by all age groups. Solving the technical problem associated with the variable peel front and variable peel force, can provide brand identity by presenting the consumer with unique opening and package shapes, while providing a constant peel front and constant peel force to the consumer.

Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:

FIG. 1 is a simple schematic diagram of a circular container of the prior art having a radially extending flange and illustrating a major diameter D, minor diameter d and length from peel front to center distance y;

FIG. 2 is a plan view of a peelable seal according to the present invention for covering a container while providing constant peel force; and

FIG. 3 is a perspective view of the peelable seal in FIG. 2 on a container;

FIG. 4 is a perspective view of the peelable seal and container of FIG. 3, showing the seal partially opened;

FIG. 5 is a plan view of another example of a peelable seal according to the present invention having a radially extending flange with a peelable seal with a constant peel force;

FIG. 6 is a perspective view of the peelable seal in FIG. 5 shown on a container;

FIG. 7 is a perspective view of the container in FIG. 6 with the peelable seal partially disengaged from the container; and

FIG. 8 is a perspective view of the container in FIG. 6 with the peelable seal further disengaged from the container.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to FIG. 1, the prior peelable seal or lid configuration is schematically illustrated for purposes of calculating the peel front which is proportional to the required peel force to remove the peelable seal or lid from a circular container having a radially extending flange with a major diameter D defining the diameter to the outside peripheral edge of the adhesive on the rim of the container, a minor diameter d, defining the diameter to the inner peripheral edge of the adhesive on the rim of the container, and a length from peel front to center distance y. The initial peel front is =2√{square root over (y(D−y))} shown at 20 in FIG. 1. Between the initial peel position and the center position the peel front is =2√{square root over (y(D−y))}−2√{square root over (y(d−y))}, shown at 22 in FIG. 1. When the peel front is at the center of the circular container, the peel front is equal to D-d, as shown at 24. It should be recognized while reviewing the equations, that the peel front initially starts out at an increased value, and drops off toward the lowest value at the center of the circular container. As the peel front continues to progress in the peel direction, the peel front increases to a greater value generally equivalent to the value at the beginning of the peel direction front A₁. Therefore, anyone opening the illustrated container encounters a varying peel front with corresponding varying peel force, which can lead to undesirable spillage of the contents from the container being opened.

Referring now to FIGS. 2-4, a peelable seal 10 according to the present invention is illustrated in plan view and in perspective view (FIGS. 3-4). The shape of the container 12 and sealing flange 14 is modified according to the present invention to provide an essentially constant peel front in order to provide a relatively constant peel force during opening. As shown in FIGS. 2-4 the container 12 and sealing flange 14 have a boat shape where the peel front initiates at one of the pointed or narrowed edges 30 a of the lid 16. The dimensions of the flange 14 can be selected to provide a constant peel force from beginning to end in the peel direction A₂ if desired. The shape of the container 12 can be various sizes and configurations provided that the sealing flange 14 is designed to provide a relatively constant peel front and corresponding relatively constant peel force when being opened. One means for providing a relatively constant peel front is to have the initial peel front initiate at a pointed configuration as shown at 30 in FIG. 2.

The narrowed or pointed initial peel front 30 remains essentially constant with the peel front at locations 32 and 34. This occurs because the surface area of the peel is greatly reduced at a pointed edge 30 in comparison to the arcuate edge 20 of a circular lid in the prior art. Other configurations can be provided. However, when the initial peel front occurs at a pointed or narrowed edge forming an acute angle, the initial peel front 30 and its respective force necessary to open the lid is significantly minimized. The peel front at the opposing end 30 b of the container 12 and lid 16 should also form an acute angle to eliminate spillage of the container contents at full removal of the lid 16.

Referring now to FIGS. 5-8, a peelable seal 40 according to the present invention can be provided for a circular container 48 having a radially extending flange 40 with a major diameter D, and minor diameter d, surrounding the container 12. The sealing flange 40 can be provided with a peelable seal 50 that progresses in a circular direction around the circumference of the circular sealing flange 40 providing a constant peel front around the entire periphery and correspondingly providing a relatively constant peel force during opening. As can best be seen in the views of FIGS. 5-7, the peelable seal 50 according to the present invention includes a perforated, scored 42 a, or otherwise tearable area 42 around the periphery of the lid 44 allowing the peel front to progressively proceed along the circumference of the sealing flange 40 while being relatively unimpeded by its continued attachment to the remaining portions 46 of the lid 44. The tearable area 42 extends and terminates essentially 270° around the circumference of the lid 44 so that the center remaining portion 46 remains attached to the tearable area 42 during removal of the lid 44 for preventing the lid 44 from falling into the contents in the container 48. The tearable area 42 commences at a tab 49 for manual gripping to initiate removal of the peelable seal 50. In this configuration, the constant surface area of the sealing flange 40 around its radially extending peripheral surface provides a constant peel front and corresponding constant peel force during opening to minimize or eliminate spillage of the contained contents. Although the illustrated example shown in FIGS. 5-8 has a circular configuration, the tearable area 42 could also extend around the periphery of various shaped lids 44. The tearable area 42 extends and terminates approximately ¾ around the periphery lid.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law. 

1. A peelable seal for a container and a corresponding lid, said seal comprising: an adhesive along peripheral edges at least one of the container and lid; and means for providing an essentially constant peel front during removal of the lid from the container.
 2. The peelable seal of claim 1, wherein the means for providing an essentially constant peel front includes the lid and container having one end as an initial peel front, said end having a pointed edge.
 3. The peelable seal of claim 2, wherein the pointed edge forms an acute angle.
 4. The peelable seal of claim 3, wherein the means for providing an essentially constant peel front includes the lid and container having an opposing end forming an acute angle.
 5. The peelable seal of claim 1, wherein the peelable seal is defined by a tearable area on the lid.
 6. The peelable seal of claim 1, wherein the means for providing an essentially constant peel front includes a tearable area that progresses in a circular direction around the circumference of the lid.
 7. The peelable seal of claim 6 wherein the tearable area extends and terminates 270° around the circumference of the lid.
 8. The peelable seal of claim 1, wherein the means for providing an essentially constant peel front includes a tearable area that progresses around the periphery of the lid.
 9. The peelable seal of claim 8, wherein the tearable area extends and terminates approximately ¾ around the periphery of the lid. 